U.S. patent application number 16/068628 was filed with the patent office on 2020-04-16 for valve mechanism and engine gas-exhaustion device provided with valve mechanism.
This patent application is currently assigned to MAZDA MOTOR CORPORATION. The applicant listed for this patent is MAZDA MOTOR CORPORATION. Invention is credited to Mitsuyuki MUROTANI, Einosuke SUEKUNI, Shuhei TSUJITA, Junji UMEMURA.
Application Number | 20200116087 16/068628 |
Document ID | / |
Family ID | 59273470 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200116087 |
Kind Code |
A1 |
MUROTANI; Mitsuyuki ; et
al. |
April 16, 2020 |
VALVE MECHANISM AND ENGINE GAS-EXHAUSTION DEVICE PROVIDED WITH
VALVE MECHANISM
Abstract
A valve mechanism includes a valve (a butterfly valve 30)
arranged in a path in which gas flows, a drive shaft (32) coupled
to the valve, and a lever member (33) attached to a lever
attachment portion (321) provided at the drive shaft. The lever
attachment portion of the drive shaft has a non-circular
cross-sectional shape. The lever member has a through-hole (331) in
a shape corresponding to a non-circular cross section of the lever
attachment portion, and is fitted onto the lever attachment
portion. The lever member is fixed to the drive shaft in such a
manner that a first contact portion (a first contact member 34) and
a second contact portion (323) sandwich the lever member in an
axial direction of the drive shaft.
Inventors: |
MUROTANI; Mitsuyuki;
(Hiroshima-shi, Hiroshima, JP) ; TSUJITA; Shuhei;
(Hatsukaichi-shi, Hiroshima, JP) ; SUEKUNI; Einosuke;
(Higashihiroshima-shi, Hiroshima, JP) ; UMEMURA;
Junji; (Higashihiroshima-shi, Hiroshima, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAZDA MOTOR CORPORATION |
Hiroshima |
|
JP |
|
|
Assignee: |
MAZDA MOTOR CORPORATION
Hiroshima
JP
|
Family ID: |
59273470 |
Appl. No.: |
16/068628 |
Filed: |
January 8, 2016 |
PCT Filed: |
January 8, 2016 |
PCT NO: |
PCT/JP2016/000083 |
371 Date: |
July 6, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D 9/101 20130101;
F02B 37/183 20130101; F02B 37/22 20130101; F16K 1/221 20130101;
Y02T 10/144 20130101; F16K 1/222 20130101; F02D 9/04 20130101; F16K
1/223 20130101; F02D 9/1065 20130101; F02B 37/02 20130101 |
International
Class: |
F02D 9/04 20060101
F02D009/04; F02D 9/10 20060101 F02D009/10; F16K 1/22 20060101
F16K001/22 |
Claims
1. A valve mechanism comprising: a valve arranged in a path in
which gas flows and configured to open/close the path; a drive
shaft coupled to the valve and configured to rotate the valve; and
a lever member attached to a lever attachment portion provided at
the drive shaft and configured to swing about the drive shaft to
rotate the drive shaft, wherein the lever attachment portion of the
drive shaft has a non-circular cross-sectional shape, and the lever
member has a through-hole in a shape corresponding to a
non-circular cross section of the lever attachment portion, is
fitted onto the lever attachment portion, and is fixed to the drive
shaft in such a manner that a first contact portion and a second
contact portion provided on the drive shaft contact a side surface
of the lever member to sandwich the lever member in an axial
direction of the drive shaft.
2. The valve mechanism according to claim 1, wherein the lever
attachment portion has a flat surface at part of a peripheral
surface thereof, and the through-hole of the lever member has, at
part of an inner peripheral surface thereof, a flat surface
configured to contact the flat surface of the lever attachment
portion.
3. The valve mechanism according to claim 1, wherein the first
contact portion includes a first contact member fitted onto the
drive shaft and separated from the drive shaft, and the second
contact portion is provided integrally with the drive shaft at a
portion adjacent to the lever attachment portion of the drive shaft
in the axial direction.
4. The valve mechanism according to claim 3, wherein the first
contact member is press-fitted onto the drive shaft.
5. An engine exhaust device including the valve mechanism according
to claim 1, comprising: an exhaust path including a first path and
a second path provided in parallel to each other, wherein the valve
is arranged in the first path, and is configured to open/close the
first path, the drive shaft extends outward of the exhaust path,
and the lever attachment portion is provided at an end portion of
the drive shaft, the end portion being separated from the exhaust
path by a predetermined distance.
6. The engine exhaust device according to claim 5, wherein the
first contact portion includes the first contact member fitted onto
the drive shaft and separated from the drive shaft, and the first
contact member is made of a material having a smaller linear
coefficient of expansion than that of the drive shaft.
Description
TECHNICAL FIELD
[0001] The technique disclosed herein relates to a valve mechanism
and an engine exhaust device including the valve mechanism.
BACKGROUND ART
[0002] Patent Document 1 describes that in a
turbosupercharger-equipped engine, an exhaust valve device is
interposed between a separate exhaust path communicating with each
cylinder and a turbine. The exhaust valve device is configured to
change, according to the rotation speed of the engine, the flow
area of exhaust gas discharged from the engine, thereby changing
the flow velocity of the exhaust gas introduced into the
turbine.
[0003] The exhaust device described in Patent Document 1 will be
described in more detail. The engine is an in-line four-cylinder
engine having four first to fourth cylinders. The separate exhaust
paths include a first exhaust path communicating with the first
cylinder, a second exhaust path at which paths communicating with
the second and third cylinders join together, and a third exhaust
path communicating with the fourth cylinder. The exhaust valve
device includes an upstream exhaust path connected to the separate
exhaust paths. A turbosupercharger includes a downstream exhaust
path connecting the upstream exhaust path and a turbine
housing.
[0004] The upstream exhaust path includes three separate paths each
communicating with the first to third exhaust paths. Each of three
paths is branched into two paths including a low-velocity path and
a high-velocity path. The downstream exhaust path has separate
low-velocity and high-velocity paths each communicating with the
low-velocity and high-velocity paths of the upstream exhaust path.
Each of the low-velocity and high-velocity paths of the downstream
exhaust path joins three separate paths of the upstream exhaust
path. A downstream end of the downstream exhaust path is connected
to an inlet of the turbine after the low-velocity and high-velocity
paths join together.
[0005] A butterfly valve is arranged in the high-velocity path of
the upstream exhaust path. A drive shaft coupled to the butterfly
valve is rotated by an actuator, and accordingly, the butterfly
valve switches between an open state and a closed state.
[0006] When the engine speed is equal to or lower than a
predetermined rotation speed, the butterfly valve is closed. In
this manner, the flow area of the exhaust gas is narrowed, and the
flow velocity of the exhaust gas is increased. Thus, turbine drive
force is increased in a low rotation range of the engine. On the
other hand, when the engine speed exceeds the predetermined
rotation speed, the butterfly valve is opened. In this manner, in a
high rotation range of the engine, the exhaust gas can be
introduced into the turbine through both of the low-velocity path
and the high-velocity path. Thus, exhaust resistance is reduced,
and the turbine drive force is increased.
[0007] Patent Document 2 describes a butterfly valve arranged in an
EGR path through which exhaust gas flows. The EGR path has first
and second paths arranged in a right-to-left direction. The
butterfly valve is arranged in each of the first and second paths,
and two butterfly valves are fixed to a valve shaft arranged to
cross the first and second paths. The valve shaft extends outward
of the EGR path, and a lever member connected to a negative
pressure type actuator is attached to a lever attachment portion
provided at an end portion of the valve shaft.
[0008] In a configuration described in Patent Document 2, the lever
attachment portion of the valve shaft is configured such that part
of a peripheral surface of the valve shaft having a circular cross
section is processed into flat surfaces. More specifically, the
lever attachment portion has two flat surfaces parallel to each
other on both sides of the center axis of the lever attachment
portion. At the lever member fitted and fixed onto the lever
attachment portion, a through-hole flattened at two portions of an
inner peripheral surface thereof is formed corresponding to the
cross-sectional shape of the lever attachment portion.
CITATION LIST
Patent Document
[0009] PATENT DOCUMENT 1: Japanese Patent Laid-Open Publication No.
2014-80900
[0010] PATENT DOCUMENT 2: Japanese Patent Laid-Open Publication No.
2011-256942
SUMMARY OF THE INVENTION
Technical Problem
[0011] As described in Patent Document 2, the lever attachment
portion is configured such that part of the peripheral surface of
the valve shaft is processed into the flat surfaces. With this
configuration, position determination between the lever member and
the lever attachment portion in a valve shaft rotation direction
can be made upon assembly. However, due to such processing, it is
difficult to ensure dimension accuracy for press-fitting the lever
member onto the lever attachment portion, and a clearance is formed
between the through-hole of the lever member and the lever
attachment portion.
[0012] In the exhaust valve device described in Patent Document 1,
when the butterfly valve arranged in the high-velocity path of the
exhaust path closes the high-velocity path, the butterfly valve
receives a high exhaust gas pressure.
[0013] Suppose that in the exhaust valve device described in Patent
Document 1, the drive shaft for opening/closing the butterfly valve
employs the attachment configuration of the lever member described
in Patent Document 2. When the butterfly valve receives the high
exhaust gas pressure, the lever member and the drive shaft rattle
due to the clearance between the through-hole of the lever member
and the lever attachment portion. For this reason, when the
butterfly valve closes the high-velocity path, noise might be
caused at an attachment portion of the lever member due to exhaust
pulsation.
[0014] The technique disclosed herein has been made in view of the
above-described points, and is intended to prevent occurrence of
noise due to rattling between a drive shaft of a valve arranged in
an exhaust path and a lever member attached to the drive shaft.
Solution to the Problem
[0015] The technique disclosed herein relates to a valve mechanism
including a valve arranged in a path in which gas flows and
configured to open/close the path, a drive shaft coupled to the
valve and configured to rotate the valve, and a lever member
attached to a lever attachment portion provided at the drive shaft
and configured to swing about the drive shaft to rotate the drive
shaft.
[0016] In the valve mechanism, the lever attachment portion of the
drive shaft has a non-circular cross-sectional shape. The lever
member has a through-hole in a shape corresponding to a
non-circular cross section of the lever attachment portion, is
fitted onto the lever attachment portion, and is fixed to the drive
shaft in such a manner that a first contact portion and a second
contact portion provided on the drive shaft contact a side surface
of the lever member to sandwich the lever member in an axial
direction of the drive shaft.
[0017] According to such a configuration, the lever member is
attached to the lever attachment portion of the drive shaft. The
lever attachment portion has the non-circular cross-sectional
shape, and the lever member has the through-hole in the shape
corresponding to the cross section of the lever attachment portion.
Thus, position determination between the lever member and the lever
attachment portion in a drive shaft rotation direction can be made
upon assembly. Meanwhile, a clearance can be formed between the
through-hole of the lever member and the lever attachment
portion.
[0018] In the above-described configuration, the first contact
portion and the second contact portion sandwich, in the axial
direction of the drive shaft, the lever member fitted onto the
lever attachment portion. The lever member is fixed to the drive
shaft by sandwiching between the first contact portion and the
second contact portion. Thus, when the valve receives the pressure
of gas flowing through the path, even if there is the clearance
between the through-hole of the lever member and the lever
attachment portion, rattling between the lever member and the drive
shaft is prevented. Thus, occurrence of noise at an attachment
portion of the lever member is prevented.
[0019] The lever attachment portion may have a flat surface at part
of a peripheral surface thereof, and the through-hole of the lever
member may have, at part of an inner peripheral surface thereof, a
flat surface configured to contact the flat surface of the lever
attachment portion.
[0020] Part of the peripheral surface of the lever attachment
portion is the flat surface. Thus, position determination between
the lever member and the lever attachment portion can be made upon
assembly while a processing step for forming the flat surface is
added. For this reason, it is difficult to ensure dimension
accuracy for press-fitting the lever member onto the lever
attachment portion.
[0021] In the above-described configuration, the lever member is
fixed to the drive shaft by sandwiching between the first contact
portion and the second contact portion. Thus, position
determination between the lever member and the lever attachment
portion can be made upon assembly while rattling between the lever
member and the drive shaft is prevented.
[0022] The first contact portion may include a first contact member
fitted onto the drive shaft and separated from the drive shaft, and
the second contact portion may be provided integrally with the
drive shaft at a portion adjacent to the lever attachment portion
of the drive shaft in the axial direction.
[0023] With this configuration, when the lever member is attached
to the lever attachment portion, the lever member is fitted onto
the drive shaft, and contacts the second contact portion provided
integrally with the drive shaft. Thereafter, the first contact
member is fitted onto the drive shaft, and contacts the lever
member. Then, the first contact member and the second contact
member sandwich the lever member. In this state, the first contact
member is fixed to the drive shaft, and in this manner, assembly of
the drive shaft and the lever member is completed.
[0024] The first contact member may be press-fitted onto the drive
shaft. With this configuration, the first contact member can be
easily fixed to the drive shaft with the lever member being
sandwiched. When the valve receives the gas pressure or the drive
shaft rotates in association with swinging of the lever member,
vibration might be caused. However, the first contact member is, by
press-fitting, fixed to the drive shaft, and therefore, there is an
advantage that the first contact member is less loosened. That is,
a state in which the first contact member is stably fixed to the
drive shaft can be maintained for a long period of time.
[0025] An engine exhaust device disclosed herein includes the
above-described valve mechanism, and an exhaust path including a
first path and a second path provided in parallel to each
other.
[0026] The valve is arranged in the first path, and is configured
to open/close the first path. The drive shaft extends outward of
the exhaust path. The lever attachment portion is provided at an
end portion of the drive shaft, the end portion being separated
from the exhaust path by a predetermined distance.
[0027] According to such a configuration, the above-described valve
mechanism is arranged in the exhaust path. Specifically, the valve
mechanism is arranged in the first path of the first and second
paths provided in parallel to each other, thereby opening/closing
the first path. When the first path is closed, exhaust gas passes
through only the second path. When the first path is opened, the
exhaust gas passes through both of the first and second paths.
[0028] Since high-temperature exhaust gas passes through the
exhaust path, the valve tends to be at high temperature. Moreover,
the temperature of the drive shaft coupled to the valve also
increases, and therefore, the drive shaft thermally expands.
[0029] In the above-described configuration, the lever attachment
portion is provided at the end portion of the drive shaft separated
from the exhaust path by the predetermined distance. Since the
lever attachment portion is separated from the exhaust path,
thermal expansion is reduced. Although the lever attachment portion
is attached to the lever member, an adverse effect due to thermal
expansion is avoided at the attachment portion of the lever
member.
[0030] The first contact portion may include the first contact
member fitted onto the drive shaft and separated from the drive
shaft, and the first contact member may be made of a material
having a smaller linear coefficient of expansion than that of the
drive shaft.
[0031] With this configuration, the amount of deformation due to
heat of the first contact member is, at the attachment portion of
the lever member, greater than the amount of deformation due to
heat of the drive shaft. As a result, even when the drive shaft
thermally expands, the first contact member can be maintained with
the first contact member being fitted onto the drive shaft.
Advantages of the Invention
[0032] As described above, according to the valve mechanism and the
engine exhaust device, the lever member fitted onto the lever
attachment portion of the drive shaft is fixed to the drive shaft
by sandwiching between the first contact portion and the second
contact portion. Thus, rattling between the lever member and the
drive shaft can be prevented, and occurrence of noise at the
attachment portion of the lever member can be prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a schematic partial sectional view of a
configuration of a turbosupercharger-equipped engine exhaust
device.
[0034] FIG. 2 is a sectional view of the configuration of the
turbosupercharger-equipped engine exhaust device.
[0035] FIG. 3 is a perspective view of a configuration of an
exhaust valve device from a turbine side.
[0036] FIG. 4 is a side view of the configuration of the exhaust
valve device.
[0037] FIG. 5 is a V-V sectional view of FIG. 3.
[0038] FIG. 6 is a schematic view for describing a VI-VI section of
FIG. 3.
[0039] FIG. 7 is an enlarged perspective view of an attachment
portion of a lever member.
[0040] FIG. 8 is a sectional view of a configuration of the
attachment portion of the lever member.
[0041] FIG. 9 is a perspective view of a lever attachment portion
and the lever member.
[0042] FIG. 10 is a sectional view of a negative pressure type
actuator.
[0043] FIG. 11 is a view for describing displacement when an output
shaft of the negative pressure type actuator advances/retreats.
[0044] FIG. 12 is a perspective view of a stopper and a stopper
engagement portion of the negative pressure type actuator.
DESCRIPTION OF EMBODIMENTS
[0045] Hereinafter, an engine exhaust device disclosed herein will
be described in detail with reference to the drawings. Note that
description below will be set forth as an example. FIGS. 1 and 2
illustrate an engine exhaust device 100. An engine illustrated in
these figures is an in-line four-cylinder four-cycle engine, and in
the present embodiment, is configured such that combustion is
performed in the order of a first cylinder, a third cylinder, a
fourth cylinder, and a second cylinder. This engine includes an
in-line four-cylinder engine body 1 having four cylinders 2A to 2D
(a first cylinder 2A, a second cylinder 2B, a third cylinder 2C,
and a fourth cylinder 2D) arranged in line. The engine exhaust
device 100 includes an exhaust manifold for exhausting exhaust gas
generated in the engine body 1, an exhaust valve device 20
described later in detail, and a turbosupercharger 50.
[0046] This engine does not include a separate component as the
exhaust manifold. Although will be described later in detail,
separate exhaust paths 14, 15, 16 of the engine body 1 (a cylinder
head 10), upstream exhaust paths 24, 25, 26 of the exhaust valve
device 20, and an exhaust introduction path portion 51 and a
junction portion 54 of the turbosupercharger 50 cooperate with each
other to form the exhaust manifold.
[0047] The engine is configured such that the turbosupercharger 50
is actuated by the exhaust gas exhausted through the exhaust
manifold to compress intake air introduced into each cylinder 2A to
2D and increase a intake air pressure. Moreover, it is configured
such that the flow velocity of the exhaust gas introduced into the
turbosupercharger 50 is, according to a vehicle operation state,
controlled by the exhaust valve device 20 interposed between the
engine body 1 and the turbosupercharger 50. With this
configuration, the effect of increasing an engine torque by the
turbosupercharger 50 is obtained across a wide range from a low
rotation range to a high rotation range of an engine rotation speed
range.
[0048] Note that in description below, for the sake of clarity of a
direction relationship, the direction of arranging the cylinders 2A
to 2D in the engine body 1 will be referred to as a "right-to-left
direction," a direction (an upper-to-lower direction in FIG. 1)
perpendicular to this direction will be referred to as a
"front-to-back direction," and a side close to the
turbosupercharger 50 will be referred to as a "front side" of the
engine, with reference to FIG. 1.
[0049] In the cylinder head 10 of the engine body 1, three separate
exhaust paths are formed for four cylinders 2A to 2D. Specifically,
the first separate exhaust path 14 used for gas exhausting of the
first cylinder 2A, the second separate exhaust path 15 used in
common for gas exhausting of the second cylinder 2B and the third
cylinder 2C not continuous in a gas exhausting sequence, and the
third separate exhaust path 16 used for gas exhausting of the
fourth cylinder 2D are formed. The second separate exhaust path 15
is in a shape branched in a Y-shape on an upstream side so that the
second separate exhaust path 15 can be used in common for the
second cylinder 2B and the third cylinder 2C.
[0050] These separate exhaust paths 14, 15, 16 are formed such that
downstream end portions thereof are gathered to the substantially
center of the cylinder head 10 in the right-to-left direction, and
open at a front surface of the cylinder head 10 in a state in which
the separate exhaust paths 14, 15, 16 are arranged close to each
other in line in the right-to-left direction.
[0051] Moreover, an EGR downstream path 18 is formed in the
cylinder head 10. As illustrated in FIG. 1, the EGR downstream path
18 is formed to cross, in the front-to-back direction, the left
side of the first cylinder 2A in the cylinder head 10. An upstream
end portion of the EGR downstream path 18 opens at a position at
the left of the first separate exhaust path 14 at the front surface
of the cylinder head 10. On the other hand, a downstream end
portion of the EGR downstream path 18 opens at a back surface of
the cylinder head 10. Note that a reference numeral "12" in FIG. 1
indicates an intake port of each cylinder 2A to 2D formed in the
cylinder head 10. The downstream end portion of the EGR downstream
path 18 opens at a position at the left of the intake port 12 of
the first cylinder 2A among the intake ports 12.
[0052] FIG. 3 illustrates the exhaust valve device 20 viewed from a
turbine side. The exhaust valve device 20 is configured to change
the flow area of the exhaust gas exhausted from the engine body 1,
thereby changing the flow velocity of the exhaust gas introduced
into the turbosupercharger 50. The exhaust valve device 20 is, with
bolts, fixed to a front surface of the engine body 1.
[0053] The exhaust valve device 20 includes a device body 21 having
three separate upstream exhaust paths 24, 25, 26 (the first
upstream exhaust path 24, the second upstream exhaust path 25, and
the third upstream exhaust path 26) each communicating with the
separate exhaust paths 14, 15, 16 of the cylinder head 10 and an
EGR intermediate path 28 communicating with the EGR downstream path
18 of the cylinder head 10; and an exhaust variable valve 3
configured to change the flow area of the exhaust gas in the
upstream exhaust paths 24, 25, 26. Note that the device body 21 is
formed of a metal casted body.
[0054] Each upstream exhaust path 24, 25, 26 is in a shape branched
in a Y-shape on a downstream side. That is, as illustrated in FIGS.
2 and 3, the first upstream exhaust path 24 has a common path 24a
communicating with the first separate exhaust path 14 of the
cylinder head 10, and a high-velocity path 24b and a low-velocity
path 24c branched into two upper and lower paths from the common
path 24a. Similarly, each of the second upstream exhaust path 25
and the third upstream exhaust path 26 has a common path 25a, 26a
(not shown) communicating with the separate exhaust path 15, 16 of
the cylinder head 10, and a high-velocity path 25b, 26b and a
low-velocity path 25c branched into two upper and lower paths from
the common path 25a, 26a. Note that in this embodiment, the
high-velocity path 24b, 25b, 26b in each upstream exhaust path 24,
25, 26 corresponds to a first path, and the low-velocity path 24c,
25c, 26c in each upstream exhaust path 24, 25, 26 corresponds to a
second path. The low-velocity path 24c, 25c, 26c is formed to have
a smaller flow path sectional area than that of the high-velocity
path 24b, 25b, 26b.
[0055] Each high-velocity path 24b, 25b, 26b has a substantially
rectangular sectional shape, and as illustrated in FIG. 3, the
high-velocity paths 24b, 25b, 26b are formed in line in the
right-to-left direction. Similarly, each low-velocity path 24c,
25c, 26c has a substantially rectangular sectional shape, and at
positions above the high-velocity paths 24b, 25b, 26b, the
low-velocity paths 24c, 25c, 26c are formed in line in the
right-to-left direction.
[0056] Meanwhile, the EGR intermediate path 28 is formed at a left
end of the device body 21 as illustrated in FIGS. 1 and 3. The EGR
intermediate path 28 has a substantially rectangular sectional
shape, and is positioned on the lower left side of the
high-velocity path 24b of the first upstream exhaust path 24.
[0057] The exhaust variable valve 3 is configured to change the
flow area of the exhaust gas in each high-velocity path 24b, 25b,
26b of the upstream exhaust paths 24, 25, 26. The exhaust variable
valve 3 includes a valve body 31 having the total of three
butterfly valves 30 each arranged in the high-velocity paths 24b,
25b, 26b, a drive shaft 32 coupled to the valve body 31, and a
negative pressure type actuator 4 configured to rotate the drive
shaft 32. The exhaust variable valve 3 rotatably drives each
butterfly valve 30 via the drive shaft 32 by the negative pressure
type actuator 4, thereby simultaneously opening/closing each
high-velocity path 24b, 25b, 26b.
[0058] A configuration of the exhaust variable valve 3 will be
specifically described herein. As illustrated in FIGS. 3 to 6, the
valve body 31 is configured to couple three butterfly valves 30
arranged in the right-to-left direction. Center portions of cross
sections of the high-velocity paths 24b, 25b, 26b arranged in the
right-to-left direction communicate with each other in the
right-to-left direction. As illustrated in FIGS. 3 and 6, the valve
body 31 is arranged to extend in the right-to-left direction and
cross the center portions of the cross sections of the
high-velocity paths 24b, 25b, 26b communicating with each other. A
support portion 311 is, at each of right and left end portions of
the valve body 31, provided integrally with the valve body 31. Each
support portion 311 has a support hole opening at an end surface.
Valve support bushes 211 attached to the device body 21 are each
inserted into two support portions 311 so that the valve body 31
can be configured to rotate about an axis X1. The valve body 31 is
exposed to high-temperature exhaust gas, and for this reason, is
made of a material exhibiting heat resistance.
[0059] As illustrated in FIGS. 3 and 5, each butterfly valve 30 is
formed in a rectangular plate shape corresponding to the sectional
shape of the high-velocity path 24b, 25b, 26b. A seating surface
241 on which the butterfly valve 30 is to be seated is formed at an
inner peripheral surface of each high-velocity path 24b, 25b, 26b.
Each butterfly valve 30 is, by rotation of the valve body 31 in a
clockwise direction in FIG. 5, switched from a state in which the
high-velocity path 24b, 25b, 26b is closed by seating of the
butterfly valve 30 on the seating surface 241 as indicated by a
solid line in FIG. 5 to a state in which the high-velocity path
24b, 25b, 26b is opened as indicated by a chain double-dashed
line.
[0060] The drive shaft 32 is coupled to the left end portion of the
valve body 31. A recessed hole 312 is formed at the left end
portion of the valve body 31. The recessed hole 312 opens at a left
end surface of the valve body 31, and is recessed along the axis of
the valve body 31. The depth of the recessed hole 312 is relatively
small.
[0061] A base end portion (i.e., a right end portion in FIG. 6) of
the drive shaft 32 is inserted into the recessed hole 312. The base
end portion of the drive shaft 32 inserted into the recessed hole
312 is fixed to the valve body 31 in such a manner that a fastening
pin 313 perpendicular to the drive shaft 32 penetrates such a base
end portion. The fastening pin 313 also penetrates the valve body
31. Both end portions of the fastening pin 313 are welded to the
valve body 31 at an outer peripheral surface of the valve body
31.
[0062] The drive shaft 32 extends outward of the left side of the
upstream exhaust paths 24, 25, 26 through a through-hole 212 formed
in the device body 21, the valve support bush 211 being inserted
into the through-hole 212. A tip end portion of the drive shaft 32
is, by a shaft support bush 213, held to rotate about the axis X1.
The shaft support bush 213 is attached to an auxiliary bearing
portion 22 provided integrally with the device body 21. As also
illustrated in FIG. 3, the auxiliary bearing portion 22 is
separated from the upstream exhaust paths 24, 25, 26 by a
predetermined distance.
[0063] As illustrated in FIGS. 4 and 7, a lever member 33 is
attached to the tip end portion of the drive shaft 32, specifically
the tip end portion of the drive shaft 32 protruding leftward of
the shaft support bush 213.
[0064] The lever member 33 is attached to a lever attachment
portion 321 provided at the tip end portion of the drive shaft 32.
As illustrated in FIGS. 8 to 10, the lever attachment portion 321
is formed in such a manner that two portions of a peripheral
surface of the drive shaft 32 are processed into a flat shape. Two
flat surfaces 322 of the lever attachment portion 321 are provided
on both sides to sandwich the axis of the drive shaft 32, and are
parallel to each other. The cross section of the lever attachment
portion 321 is in a non-circular shape.
[0065] The lever member 33 has a through-hole 331 corresponding to
the cross sectional shape of the lever attachment portion 321. As
illustrated in FIGS. 8 and 9, the through-hole 331 has, at an inner
peripheral surface thereof, two parallel flat surfaces 3311. The
lever member 33 is fitted onto the lever attachment portion 321.
The cross sectional shape of the lever attachment portion 321 is
the non-circular shape, and the through-hole 331 of the lever
member 33 corresponds to the cross sectional shape of the lever
attachment portion 321. Thus, position determination in a rotation
direction of the drive shaft 32 when the lever member 33 is
assembled with the drive shaft 32 is facilitated.
[0066] At a portion of the lever attachment portion 321 of the
drive shaft 32 adjacent to the butterfly valve 30, a second contact
portion 323 configured to contact a side surface of the lever
member 33 is provided integrally with the drive shaft 32. The
second contact portion 323 is formed at the drive shaft 32 in such
a manner that flattening as described above is performed for the
drive shaft 32.
[0067] At a portion of the lever attachment portion 321 of the
drive shaft 32 adjacent to the opposite side of the butterfly valve
30, a press-fitting portion 324 is formed. The cross section of the
press-fitting portion 324 has a circular shape with a smaller
diameter than that of the drive shaft 32. The press-fitting portion
324 has a smaller diameter than that of the lever attachment
portion 321, and a step is provided between the press-fitting
portion 324 and the lever attachment portion 321.
[0068] The press-fitting portion 324 is press-fitted in a first
contact member 34 separated from the drive shaft 32. The first
contact member 34 is a discoid member formed with a larger diameter
than that of the drive shaft 32, and at the center thereof, has a
through-hole with a circular cross section. The first contact
member 34 is fixed to the drive shaft 32 in such a manner that the
press-fitting portion 324 is press-fitted in the first contact
member 34. The first contact member 34 press-fitted onto the
press-fitting portion 324 contacts the side surface of the lever
member 33. The lever member 33 is firmly fixed to the drive shaft
32 in such a manner that the lever member 33 is sandwiched between
the first contact member 34 and the second contact portion 323 in
an axial direction of the drive shaft 32.
[0069] As illustrated in FIG. 9, a groove 325 extending across the
entire circumference is formed at a further tip end portion of the
drive shaft 32. An E-ring 326 for avoiding detachment of the first
contact member 34 is attached to the groove 325.
[0070] As illustrated in FIG. 8 etc., the lever member 33 has a pin
332 provided at a position apart from the center of the
through-hole 331, i.e., the axis X1 of the drive shaft 32, by a
predetermined distance. The pin 332 is parallel to the drive shaft
32. A tip end of an output shaft 44 of the negative pressure type
actuator 4 is coupled to the pin 332.
[0071] As illustrated in FIGS. 3 and 4, the negative pressure type
actuator 4 is positioned close to a turbine 56 with respect to the
device body 21, and is fixed to the device body 21 via a bracket 45
provided at the negative pressure type actuator 4. As illustrated
in FIGS. 10 and 11, the negative pressure type actuator 4 includes
a first casing 41, a second casing 42, a diaphragm 43, and the
output shaft 44.
[0072] Each of the first casing 41 and the second casing 42 is in a
cup shape, and the first casing 41 and the second casing 42 are
joined together. With this configuration, a space is formed inside
the negative pressure type actuator 4.
[0073] The diaphragm 43 is interposed between the first casing 41
and the second casing 42. The diaphragm 43 divides the inner space
of the negative pressure type actuator 4 into a negative pressure
chamber 410 positioned close to the first casing 41 and a positive
pressure chamber 420 positioned close to the second casing 42.
[0074] The output shaft 44 is connected to the diaphragm 43. The
output shaft 44 extends toward the opposite side of the negative
pressure chamber 410 through a through-hole 421 formed at the
second casing 42. As described above, a tip end portion of the
output shaft 44 is coupled to the pin 332 of the lever member 33.
The output shaft 44 extends downward diagonally from the device
body 21 toward the turbine 56. The output shaft 44 is configured to
advance/retreat in association with displacement of the diaphragm
43. In association with advancing/retreating of the output shaft
44, the lever member 33 swings about the axis X1 of the drive shaft
32, and the drive shaft 32 rotates about the center of the axis X1,
as illustrated in FIG. 11.
[0075] A bush 422 is attached to the inside of the through-hole 421
of the second casing 42. The bush 422 is fitted onto the output
shaft 44. The bush 422 closely contacts the output shaft 44,
thereby holding an airtight state in the positive pressure chamber
420. Note that when the output shaft 44 advances/retreats, the bush
422 allows sliding of the output shaft 44.
[0076] A negative pressure pipe 411 is connected to a bottom
portion of the first casing 41. A intake air negative pressure is
supplied/released to/from the negative pressure chamber 410 through
the negative pressure pipe 411. A compression spring 412 is
arranged in the negative pressure chamber 410. The compression
spring 412 biases the diaphragm 43 in the direction of advancing
the output shaft 44. Note that FIG. 10 illustrates a state in which
the negative pressure is supplied to the negative pressure chamber
410. A communication hole 423 allowing communication between the
inside and the outside of the second casing 42 is provided at the
second casing 42. The inside of the positive pressure chamber 420
is held at an atmospheric pressure. When the negative pressure is
supplied to the negative pressure chamber 410, the output shaft 44
moves in a retreating direction, i.e., toward a negative pressure
chamber side, due to a difference in a pressure acting on the
diaphragm 43 between the negative pressure chamber 410 and the
positive pressure chamber 420. When the negative pressure is
released from the negative pressure chamber 410, the output shaft
44 moves in an advancing direction, i.e., toward the opposite side
of the negative pressure chamber side, due to biasing force of the
compression spring 412.
[0077] A stopper 46 is attached to the bracket 45 of the negative
pressure type actuator 4. Note that in the present embodiment, the
bracket 45 is attached on the track of advancing/retreating of the
output shaft 44. The stopper 46 may be attached to the bracket 45
as long as the stopper 46 is attached on the track of
advancing/retreating of the output shaft 44. For example, in a case
where the bracket 45 is attached to other portions than a portion
on the track, the stopper 46 may be directly attached to a body of
the negative pressure type actuator 4.
[0078] A stopper engagement portion 47 to be engaged with the
stopper 46 is fixed to the output shaft 44. The stopper 46 and the
stopper engagement portion 47 engage with each other when the
output shaft 44 moves in the retreating direction, thereby
preventing the output shaft 44 from further moving in the
retreating direction.
[0079] As illustrated in FIGS. 11 and 12, the stopper 46 is a
hat-shaped member, and a passing hole 461 through which the output
shaft 44 passes is formed at a center position of the stopper 46.
The passing hole 461 has a sufficiently-larger diameter than the
diameter of the output shaft 44. As will be described later, the
output shaft 44 is inclined upon advancing/retreating. The diameter
of the passing hole 461 is set as described above, and therefore,
contact of the output shaft 44 with the passing hole 461 is avoided
even when the output shaft 44 is inclined.
[0080] Moreover, the stopper 46 has, at the center position
including the passing hole 461, a first contact surface 462
expanding in a raised shape. As illustrated in FIG. 11, the first
contact surface 462 corresponds to a spherical surface about a
center position C of the bush 422 holding the output shaft 44.
[0081] The stopper engagement portion 47 is fixed to an
intermediate position of the output shaft 44. The stopper
engagement portion 47 has a second contact surface 471 configured
to contact the first contact surface 462 of the stopper 46. The
second contact surface 471 is in a recessed spherical surface
shape. As illustrated in FIG. 11, the second contact surface 471
corresponds to a spherical surface about the center position C of
the bush 422.
[0082] In the exhaust valve device 20 with this configuration, when
the exhaust variable valve 3 is closed, the intake air negative
pressure is supplied to the negative pressure chamber 410 of the
negative pressure type actuator 4 (i.e., the negative pressure type
actuator is turned ON). This brings a state in which the output
shaft 44 is pulled in the retreating direction. Thus, the lever
member 33 is positioned in a state illustrated in FIG. 10, and each
butterfly valve 30 closes the high-velocity path 24b, 25b, 26b as
indicated by the solid line in FIG. 5.
[0083] On the other hand, when the exhaust variable valve 3 is
opened, the intake air negative pressure is released from the
negative pressure chamber 410 of the negative pressure type
actuator 4 (i.e., the negative pressure type actuator is turned
OFF). This brings a state in which the output shaft 44 is pushed
out in the advancing direction due to the biasing force of the
compression spring 412. Thus, the lever member 33 rotates
clockwise, and the lever member 33 is positioned in a state
illustrated in FIG. 4. Each butterfly valve 30 opens the
high-velocity path 24b, 25b, 26b as indicated by the chain
double-dashed line in FIG. 5. The exhaust variable valve 3 is
configured as being normally opened.
[0084] The stopper engagement portion 47 attached to the middle of
the output shaft 44 and the stopper 46 attached to the bracket 45
form a configuration for restricting the amount of movement of the
output shaft 44 when the negative pressure is supplied to the
negative pressure type actuator 4. Thus, in a state in which the
stopper engagement portion 47 and the stopper 46 engage with each
other, no pull-in force of the negative pressure type actuator 4
acts on the drive shaft 32. For such a state, a configuration may
be employed, in which when the negative pressure is, for example,
supplied to the negative pressure type actuator 4, the stopper
attached to a predetermined position contacts the lever member 33
to restrict further swinging of the lever member 33. However, in
this configuration, the pull-in force of the negative pressure type
actuator 4 acts on the drive shaft 32 with the lever member 33
contacting the stopper (i.e., with the butterfly valves 30 being
closed).
[0085] As described above, the exhaust variable valve 3 is
configured such that the drive shaft 32 is coupled to the left end
portion of the valve body 31. It is not configured such that the
drive shaft 32 penetrates the valve body 31 in the right-to-left
direction and is supported at the right of the valve body 31 by the
device body 21, but the coupling-side end portion (i.e., the right
end portion in FIG. 6) of the drive shaft 32 is welded to a middle
position of the valve body 31 in the right-to-left direction. Thus,
when a configuration in which the pull-in force of the negative
pressure type actuator 4 acts on the end portion of the drive shaft
32 with the butterfly valves 30 being closed is employed, the left
end portion of the drive shaft 32 is pulled downward in the plane
of paper of FIG. 6, i.e., toward the turbine 56. Accordingly, the
right end portion of the drive shaft 32, which is supported by the
shaft support bush 213, in the recessed hole 312 pushes the valve
body 31 upward in the plane of paper, i.e., toward the engine body
1. Meanwhile, the valve body 31 closing the high-velocity paths
24b, 25b, 26b is periodically pushed in a direction from the engine
body 1 toward the turbine 56 due to exhaust pulsation. As a result,
there is a probability that the valve body 31 vibrates.
[0086] On the other hand, in the above-described configuration,
when the butterfly valves 30 are closed, the stopper engagement
portion 47 attached to the middle of the output shaft 44 engages
with the stopper 46. With this configuration, in a state in which
the butterfly valves 30 are closed, no pull-in force of the
negative pressure type actuator 4 acts on the drive shaft 32. Thus,
in the above-described configuration, vibration of the valve body
31 due to exhaust pulsation can be prevented.
[0087] As illustrated in FIGS. 1 and 2, the turbosupercharger 50
is, with bolts, fixed to the device body 21 of the exhaust valve
device 20. The turbosupercharger 50 includes the exhaust
introduction path portion 51 fixed to an attachment surface 21a
(see FIG. 3) of the device body 21, a turbine housing 52 continuous
to the exhaust introduction path portion 51, the turbine 56
arranged in the turbine housing 52, and a compressor coupled to the
turbine 56 via a coupling shaft 57 and arranged in a not-shown
intake air path.
[0088] The exhaust introduction path portion 51 has separate
high-velocity path 51b and low-velocity path 51c communicating with
each of the high-velocity paths 24b, 25b, 26b and the low-velocity
paths 24c, 25c, 26c of the exhaust valve device 20. Although not
specifically shown in the figure, the high-velocity path 51b of the
exhaust introduction path portion 51 joins three separate
high-velocity paths 24b, 25b, 26b in the exhaust valve device 20.
Similarly, the low-velocity path 51c of the exhaust introduction
path portion 51 joins three separate low-velocity paths 24c, 25c,
26c in the exhaust valve device 20.
[0089] The exhaust introduction path portion 51 includes, at a
downstream end portion thereof, the junction portion 54 at which
the high-velocity path 51b and the low-velocity path 51c join
together. The exhaust gas from the high-velocity path 51b of the
exhaust introduction path portion and the exhaust gas from the
low-velocity path 51c of the exhaust introduction path portion join
together at the junction portion 54, and then, are sent to the
turbine 56.
[0090] As described above, this engine does not include the
separate component as the exhaust manifold, and the separate
exhaust paths 14, 15, 16 of the engine body 1 (the cylinder head
10), the upstream exhaust paths 24, 25, 26 of the exhaust valve
device 20, and the exhaust introduction path portion 51 and the
junction portion 54 of the turbosupercharger 50 are combined to
form the exhaust manifold.
[0091] Moreover, an EGR upstream path 58 communicating with the EGR
intermediate path 28 of the exhaust valve device 20 is formed at a
portion at the left of the exhaust introduction path portion 51 of
the turbine housing 52. Part of the exhaust gas flowing into the
turbosupercharger 50 is, as EGR gas, introduced into the intake air
path through the EGR upstream path 58, the EGR intermediate path
28, and the EGR downstream path 18. That is, in this engine, the
EGR downstream path 18, the EGR intermediate path 28, and the EGR
upstream path 58 form an EGR path.
[0092] In the engine configured as described above, the exhaust gas
generated in the engine body 1 is introduced into the
turbosupercharger 50 from the separate exhaust paths 14, 15, 16
through the upstream exhaust paths 24, 25, 26 of the exhaust valve
device 20. At this point, the flow area of the exhaust gas flowing
in each high-velocity path 24b, 25b, 26b of the exhaust valve
device 20 is changed according to the vehicle operation state.
[0093] Specifically, in the low rotation range in which the
rotation speed of the engine body 1 is equal to or lower than a
predetermined rotation speed (e.g., 1600 rpm), the exhaust valve
device 20 is controlled such that the high-velocity paths 24b, 25b,
26b are closed. That is, the intake air negative pressure is
supplied to the negative pressure chamber 410 of the negative
pressure type actuator 4, and in this manner, the state in which
the output shaft 44 is pulled in the retreating direction is
brought. Thus, the lever member 33 is positioned in the state
illustrated in FIG. 10, and each butterfly valve 30 closes the
high-velocity path 24b, 25b, 26b as indicated by the solid line in
FIG. 5. In this manner, a small amount of exhaust gas is
concentrated on the low-velocity paths 24c, 25c, 26c, and
therefore, the flow velocity of the exhaust gas is increased. This
increases drive force of the turbine 56 of the turbosupercharger
50, thereby increasing the boost pressure.
[0094] On the other hand, in the high rotation range in which the
rotation speed of the engine body 1 exceeds the predetermined
rotation speed, there is a probability that scavenging performance
is lowered due to path resistance when passage of the exhaust gas
is allowed by means of only the low-velocity paths 24c, 25c, 26c.
For this reason, the exhaust valve device 20 is controlled such
that the high-velocity paths 24b, 25b, 26b are opened. That is, the
intake air negative pressure is released from the negative pressure
chamber 410 of the negative pressure type actuator 4, and in this
manner, the state in which the output shaft 44 is pushed out in the
advancing direction due to the biasing force of the compression
spring 412 is brought. Thus, the lever member 33 is positioned in
the state illustrated in FIG. 4, and each butterfly valve 30 opens
the high-velocity path 24b, 25b, 26b as indicated by the chain
double-dashed line in FIG. 5. The exhaust gas is introduced into
the turbosupercharger 50 through both of the high-velocity paths
24b, 25b, 26b and the low-velocity paths 24c, 25c, 26c. Thus,
lowering of the scavenging performance due to the exhaust path
resistance is reduced while the turbosupercharger 50 is driven to
increase the boost pressure.
[0095] In the exhaust device configured as described above, the
valve body 31 receives a high exhaust gas pressure when each
high-velocity path 24b, 25b, 26b is closed.
[0096] As illustrated in FIG. 9 etc., the lever attachment portion
321 of the drive shaft 32 is processed to have two flat surfaces
322 for position determination of the lever member 33. By such
processing, dimension accuracy for press-fitting the lever member
33 onto the lever attachment portion 321 cannot be ensured, and a
clearance is formed between the through-hole 331 of the lever
member 33 and the lever attachment portion 321. In a state in which
the clearance is present, when the valve body 31 receives the gas
pressure, the lever member 33 and the drive shaft 32 rattle. Since
the exhaust variable valve 3 is closed in the low rotation range of
the engine body 1 as described above, there is a probability that
noise is caused in the vicinity of the attachment portion of the
lever member 33 due to exhaust pulsation in the low rotation range
of the engine body 1.
[0097] In particular, the valve body 31 is exposed to the
high-temperature exhaust gas, and for this reason, is made of the
material exhibiting heat resistance. Considering a difficulty in
processing of such a material, the drive shaft 32 coupled to the
valve body 31 is, as illustrated in FIG. 6, inserted into the
recessed hole 312 formed at the left end portion of the solid valve
body 31, and is fixed to the valve body 31 with the fastening pin
313. In this configuration, when the valve body 31 receives the gas
pressure in each high-velocity path 24b, 25b, 26b, the left end
portion of the drive shaft 32 separated from the valve body 31 is
easily movable. That is, this configuration is a configuration in
which the lever member 33 and the drive shaft 32 easily rattle.
[0098] However, in the above-described configuration, the lever
member 33 is, in the axial direction of the drive shaft 32,
sandwiched between the first contact member 34 press-fitted onto
the press-fitting portion 324 of the drive shaft 32 and the second
contact portion 323 provided integrally with the drive shaft 32.
With this configuration, the lever member 33 is firmly fixed to the
drive shaft 32. This prevents rattling of the lever member 33 and
the drive shaft 32 when the valve body 31 receives the gas
pressure. Occurrence of the noise at the attachment portion of the
lever member 33 is prevented.
[0099] The first contact member 34 described herein is configured
as the component separated from the drive shaft 32, and the second
contact portion 323 is provided integrally with the second contact
portion 323. Thus, the drive shaft 32 and the lever member 33 can
be easily assembled together.
[0100] The first contact member 34 is fitted onto the press-fitting
portion 324 of the drive shaft 32. With this configuration, even
when vibration is caused due to the gas pressure received by the
valve body 31 or rotation of the drive shaft 32 in association with
swinging of the lever member 33, the first contact member 34 is
less loosened, and the state of stably fixing the first contact
member 34 to the drive shaft 32 can be maintained for a long period
of time. As described above, the predetermined rotation speed for
switching opening/closing of the butterfly valve 30 is set to,
e.g., 1600 rpm, and therefore, the frequency of opening/closing of
the butterfly valve 30 is high. Thus, stable fixing of the first
contact member 34 to the drive shaft 32 for the long period of time
enhances reliability of the exhaust device 100.
[0101] Further, the valve body 31 arranged in the high-velocity
paths 24b, 25b, 26b reaches a high temperature, and the drive shaft
32 coupled to the valve body 31 also reaches a high temperature.
This leads to thermal expansion. Thus, the lever attachment portion
321 of the drive shaft 32 is separated from the high-velocity paths
24b, 25b, 26b by a predetermined distance, and therefore, thermal
expansion at the attachment portion between the drive shaft 32 and
the lever member 33 is reduced. As a result, an adverse effect due
to thermal expansion can be avoided at the attachment portion
between the drive shaft 32 and the lever member 33. In the present
embodiment, the drive shaft 32 extends to the vicinity of the tip
end of the output shaft 44, and the lever attachment portion 321 is
provided at one end portion of the drive shaft 32. Thus, the lever
attachment portion 321 is sufficiently separated from the
high-velocity paths 24b, 25b, 26b.
[0102] The first contact member 34 described herein is made of a
material having a smaller linear coefficient of expansion than that
of the drive shaft 32. With this configuration, the amount of
deformation due to heat of the drive shaft 32 is, at the attachment
portion of the lever member 33, greater than the amount of
deformation due to heat of the first contact member 34. Thus, even
when the drive shaft 32 is thermally expanded, the first contact
member 34 can be maintained at a state in which the first contact
member 34 is press-fitted onto the drive shaft 32.
[0103] Note that in the above-described configuration, the lever
attachment portion 321 is configured such that two portions of the
peripheral surface thereof are in the flat surface shape, but may
be configured such that a single portion of the peripheral surface
thereof is in a flat surface shape. Moreover, as long as the cross
section of the lever attachment portion 321 is at least formed in
the non-circular shape, position determination of the lever member
33 is facilitated. Note that the through-hole of the lever member
33 is formed in a shape corresponding to the cross sectional shape
of the lever attachment portion 321.
[0104] In the above-described configuration, the first contact
member 34 is fixed to the drive shaft 32 by press-fitting onto the
drive shaft 32. However, the first contact member 34 may be fixed
to the drive shaft 32 in other methods than press-fitting. For
example, the first contact member 34 may be fixed to the drive
shaft 32 by a method such as screwing.
[0105] Note that the first contact member 34 as the member
separated from the drive shaft 32 is not necessarily prepared. The
lever member 33 may be fixed to the drive shaft 32 in such a manner
that a flange-shaped first contact portion is provided by crushing
of the end portion of the drive shaft 32 after the lever member 33
is fitted onto the lever attachment portion 321 and the lever
member 33 is sandwiched between the first contact portion and the
second contact portion 323. In this configuration, rattling of the
lever member 33 and the drive shaft 32 can be also prevented.
[0106] Moreover, this technique is not limited to a valve mechanism
including the butterfly valves 30, and is broadly applicable to a
valve mechanism including a valve configured to rotate by a drive
shaft.
[0107] In the exhaust device 100 configured as described above, the
output shaft 44 of the negative pressure type actuator 4 not only
advances/retreats in an axial direction thereof, but also
advances/retreats while being inclined. Specifically, as
illustrated in FIG. 11, the lever member 33 swings about the axis
X1 of the drive shaft 32, and therefore, the pin 332 of the lever
member 33 displaces along an arc about the axis X1 of the drive
shaft 32 as indicated by a solid line and a dashed line in FIG. 11.
The tip end of the output shaft 44 of the negative pressure type
actuator 4 is connected to the pin 332, and therefore, the axis X2
of the output shaft 44 indicated by chain lines in FIG. 11 is, in
association with advancing/retreating of the output shaft 44,
inclined about a pivot point, i.e., the center position C of the
bush 422. Note that "inclination of the output shaft 44" means that
the angle of the output shaft 44 arranged between the lever member
33 and the negative pressure type actuator 4 changes.
[0108] When the stopper 46 and the stopper engagement portion 47
contact with each other, if the stopper 46 and the stopper
engagement portion 47 are not in surface contact but in point
contact with each other, an impact load is locally input to the
stopper 46. Moreover, when it is configured such that the output
shaft 44 is moved at high speed for enhancing responsiveness when
the exhaust variable valve 3 is closed by a supply of the intake
air negative pressure to the negative pressure chamber 410 of the
negative pressure type actuator 4, the impact load locally input to
the stopper 46 further increases. As described above, the frequency
of opening/closing the exhaust variable valve 3 is relatively high.
Thus, there is a probability that reliability and durability of the
configurations of the stopper 46 and the stopper engagement portion
47 for restricting the amount of movement of the output shaft of
the negative pressure type actuator 4 are lowered.
[0109] In the above-described configuration, the first contact
surface 462 of the stopper 46 is formed in the spherical surface
shape about the center position C of the bush 422, and the second
contact surface 471 of the stopper engagement portion 47 is formed
in the recessed spherical surface shape about the center position C
of the bush 422. With this configuration, the stopper engagement
portion 47 comes into surface contact with the stopper 46 even when
the output shaft 44 is inclined. As a result, local input of the
impact load on the stopper is avoided. Even when contact between
the stopper 46 and the stopper engagement portion 47 is repeated
for enhancing operation responsiveness of the butterfly valve 30,
the impact load can be received by the surface, and therefore, high
reliability and durability can be ensured.
[0110] When the length of the drive shaft 32 in the axial direction
thereof is increased due to thermal expansion, the output shaft 44
of the negative pressure type actuator 4 is inclined with respect
to the axial direction of the drive shaft 32. The stopper 46 is
configured such that the first contact surface 462 is in the
spherical surface shape, and the stopper engagement portion 47 is
configured such that the second contact surface 471 is in the
recessed spherical surface shape. Thus, even when the output shaft
44 is inclined in the direction of the drive shaft 32, the stopper
46 and the stopper engagement portion 47 are in surface contact
with each other. Thus, local input of the impact load to the
stopper 46 is also avoided upon thermal expansion of the drive
shaft 32.
[0111] Note that in the above-described configuration, the first
contact surface 462 of the stopper 46 is in the spherical surface
shape, and the second contact surface 471 of the stopper engagement
portion 47 is in the recessed spherical surface shape. However, the
shapes of the first contact surface 462 and the second contact
surface 471 are not limited to the spherical shape. As illustrated
in FIG. 11, the output shaft 44 is inclined in the section
including the axis X2. Thus, the first contact surface 462 of the
stopper 46 may be an arc-shaped surface at least in the
above-described section. Similarly, the second contact surface 471
of the stopper engagement portion 47 may be an arc-shaped surface
with the same curvature as that of the first contact surface 462 at
least in the above-described section.
[0112] The first contact surface 462 may be in a recessed spherical
shape, and the second contact surface 471 may be in a spherical
shape to contact the first contact surface 462. Similarly, in a
configuration in which the first contact surface 462 and the second
contact surface 471 are arc-shaped surfaces at least in the
above-described section, a raised-recessed relationship between the
first contact surface 462 and the second contact surface 471 may be
interchanged.
[0113] Note that the engine of the above-described embodiment is an
example of a preferable embodiment of a turbosupercharger-equipped
multiple-cylinder engine. Specific configurations of the engine and
the exhaust valve device 20 incorporated into the engine can be
changed as necessary without departing from the gist of the present
invention.
[0114] Moreover, in the above-described embodiment, the example
where the exhaust device is applied to the in-line four-cylinder
four-cycle engine has been described. However, the exhaust device
disclosed herein is, needless to say, also applicable to other
engines than that of the above-described embodiment.
DESCRIPTION OF REFERENCE CHARACTERS
[0115] (1) Engine Body [0116] (100) Exhaust device [0117] (24b),
(25b), (26b) High-Velocity Path (First Path) [0118] (24c), (25c),
(26c) Low-Velocity Path (Second Path) [0119] (30) Butterfly Valve
(Valve) [0120] (32) Drive Shaft [0121] (321) Lever Attachment
Portion [0122] (322) Flat Surface [0123] (323) Second Contact
Portion [0124] (33) Lever Member [0125] (331) Through-Hole [0126]
(3311) Flat Surface [0127] (34) First Contact Member (First Contact
Portion) [0128] (4) Negative Pressure Type Actuator [0129] (41)
First Casing [0130] (410) Negative Pressure Chamber [0131] (42)
Second Casing [0132] (43) Diaphragm [0133] (44) Output Shaft [0134]
(46) Stopper [0135] (462) First Contact Surface [0136] (47) Stopper
Engagement Portion [0137] (471) Second Contact Surface
* * * * *